As a nurse (a very long time ago) dealing with people who suffered this as a matter of course, we had "manual evacuation days". This was very unpleasant for the patients and not much fun for the nurses either.

To avoid having too many on our list, we would start with laxatives taken orally, progress the following day to liquid paraffin taken orally and then a suppository just before the last resort of manual evacuation.

I had success with a glycerin based suppository (ask your pharmacist) and then getting the patient to squat on the toilet seat rather than sitting on it (relaxes the relevant muscles which lessens the pain) and then push on the belly area. They would also have to be patient as the motion could take a while. Reading is good, sudokus are good, crosswords are good but you have to remember to keep straining.

The only problem with the squat is that toilets are not really designed for this and success may also require a bit of clean up if your aim is a bit off. Take old towels with you just in case and keep the toilet brush handy. This is still preferable to the digital or manual evacuation method which is even more messy.